Nowadays, homes are increasingly equipped with energy generators, such as photovoltaic power generation (PV) systems and fuel cells (FC), or energy storage apparatuses, such as rechargeable batteries. In addition, home energy management systems (HEMS) are conspicuously spreading. HEMS is expected as a system that enables energy conservation, reduction in cost, or practical use of renewable energy.
In Japan, feed in tariff (FIT) for renewable energy started on Jul. 1, 2012. Under the system, in a double power generation mode contract, a power selling amount derived from the PV system can be increased by covering the energy demand in PV power generation with discharge of the rechargeable battery. Specifically, in the double power generation mode, a push-up effect for the power selling amount can be expected by discharging private power-generation facilities. The double power generation mode has a form in which private power-generation facilities (such as a rechargeable battery) are placed together with the PV system.
To pursue reduction in heating and lighting expenses under such a condition, it is necessary to make a discharge strategy for the rechargeable battery, with the push-up effect taken into consideration. To prepare a discharge strategy, it is required to consider estimated values of an energy demand and a PV power generation amount of a customer's home. However, estimated values are different from values (actual values) in actual use in many cases, and there are cases where expected reduction in heating and lighting expenses cannot be achieved.